From: Jeremy Walker <jez.walker@...>
Date: 2012-05-14T21:16:35+09:00
Subject: Re: Accessing child variables

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On 14 May 2012 12:50, Stuart Morrison <lists@ruby-forum.com> wrote:

> Hi
>
> I am learning ruby and I am trying to access variables from a child
> object.  Can anyone help me access the following variable please?
>
>  class A
>     attr_accessor :valA
>  end
>
>  class B
>    attr_accessor :myarray
>
>    def initialize
>      @myarray = []
>    end
>
>    def myarray
>      @myarray = myarray
>    end
>  end #end Class
>
>  class My_top
>
>    attr_accessor :c
>
>    c = B.new
>
>    objA = A.new
>
>    objA.valA = 10
>
>    c.myarray << objA
>
> end
>
>  my_top = My_top.new
>  puts my_top.c.myarray.inspect
>
>
> My error is as follows:
>
> stack level too deep (SystemStackError)
>

This is a hint to you that a method you are calling is calling itself.

If you look at your implementation of myarray, you have "@myarray =
myarray". This means that when you call myarray, it's calling itself over
and over again. This is recursion and in this situation, this is bad.

At the top of your class you have "attr_accessor :myarray"

That in effect defines the following two methods:
def myarray
  return @myarray
end

def myarray=(arr)
  @myarray = arr
end

Your method of "myarray" is overriding the default one and causing the
problem. Try removing it and see if that fixes it.

Jeremy Walker


>
> --
> Posted via http://www.ruby-forum.com/.
>
>

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<br><br><div class=3D"gmail_quote">On 14 May 2012 12:50, Stuart Morrison <s=
pan dir=3D"ltr">&lt;<a href=3D"mailto:lists@ruby-forum.com" target=3D"_blan=
k">lists@ruby-forum.com</a>&gt;</span> wrote:<br><blockquote class=3D"gmail=
_quote" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:=
1ex">

Hi<br>
<br>
I am learning ruby and I am trying to access variables from a child<br>
object. =A0Can anyone help me access the following variable please?<br>
<br>
 =A0class A<br>
 =A0 =A0 attr_accessor :valA<br>
 =A0end<br>
<br>
 =A0class B<br>
 =A0 =A0attr_accessor :myarray<br>
<br>
 =A0 =A0def initialize<br>
 =A0 =A0 =A0@myarray =3D []<br>
 =A0 =A0end<br>
<br>
 =A0 =A0def myarray<br>
 =A0 =A0 =A0@myarray =3D myarray<br>
 =A0 =A0end<br>
 =A0end #end Class<br>
<br>
 =A0class My_top<br>
<br>
 =A0 =A0attr_accessor :c<br>
<br>
 =A0 =A0c =3D B.new<br>
<br>
 =A0 =A0objA =3D A.new<br>
<br>
 =A0 =A0objA.valA =3D 10<br>
<br>
 =A0 =A0c.myarray &lt;&lt; objA<br>
<br>
end<br>
<br>
 =A0my_top =3D My_top.new<br>
 =A0puts my_top.c.myarray.inspect<br>
<br>
<br>
My error is as follows:<br>
<br>
stack level too deep (SystemStackError)<br></blockquote><div><br></div><div=
>This is a hint to you that a method you are calling is calling itself.</di=
v><div><br></div><div>If you look at your implementation of=A0myarray, you =
have &quot;@myarray =3D myarray&quot;. This means that when you call myarra=
y, it&#39;s calling itself over and over again. This is recursion and in th=
is situation, this is bad.</div>

<div><br></div><div>At the top of your class you have &quot;attr_accessor :=
myarray&quot;</div><div><br></div><div>That in effect defines the following=
 two methods:=A0</div><div>def myarray</div><div>=A0 return @myarray</div>
<div>
end</div><div><br></div><div>def myarray=3D(arr)</div><div>=A0 @myarray =3D=
 arr</div><div>end</div><div><br></div><div>Your method of &quot;myarray&qu=
ot; is overriding the default one and causing the problem. Try removing it =
and see if that fixes it.</div>

<div><br></div><div>Jeremy Walker</div><div>=A0</div><blockquote class=3D"g=
mail_quote" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-l=
eft:1ex">
<span class=3D"HOEnZb"><font color=3D"#888888"><br>
--<br>
Posted via <a href=3D"http://www.ruby-forum.com/" target=3D"_blank">http://=
www.ruby-forum.com/</a>.<br>
<br>
</font></span></blockquote></div><br>

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